projects/linux·blob v2.6.16 · refs

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1/*
2 * "Optimize" a list of dependencies as spit out by gcc -MD
3 * for the kernel build
4 * ===========================================================================
5 *
6 * Author Kai Germaschewski
7 * Copyright 2002 by Kai Germaschewski <[email protected]>
8 *
9 * This software may be used and distributed according to the terms
10 * of the GNU General Public License, incorporated herein by reference.
11 *
12 *
13 * Introduction:
14 *
15 * gcc produces a very nice and correct list of dependencies which
16 * tells make when to remake a file.
17 *
18 * To use this list as-is however has the drawback that virtually
19 * every file in the kernel includes <linux/config.h> which then again
20 * includes <linux/autoconf.h>
21 *
22 * If the user re-runs make *config, linux/autoconf.h will be
23 * regenerated. make notices that and will rebuild every file which
24 * includes autoconf.h, i.e. basically all files. This is extremely
25 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m.
26 *
27 * So we play the same trick that "mkdep" played before. We replace
28 * the dependency on linux/autoconf.h by a dependency on every config
29 * option which is mentioned in any of the listed prequisites.
30 *
31 * To be exact, split-include populates a tree in include/config/,
32 * e.g. include/config/his/driver.h, which contains the #define/#undef
33 * for the CONFIG_HIS_DRIVER option.
34 *
35 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
36 * which depend on "include/linux/config/his/driver.h" will be rebuilt,
37 * so most likely only his driver ;-)
38 *
39 * The idea above dates, by the way, back to Michael E Chastain, AFAIK.
40 *
41 * So to get dependencies right, there are two issues:
42 * o if any of the files the compiler read changed, we need to rebuild
43 * o if the command line given to the compile the file changed, we
44 * better rebuild as well.
45 *
46 * The former is handled by using the -MD output, the later by saving
47 * the command line used to compile the old object and comparing it
48 * to the one we would now use.
49 *
50 * Again, also this idea is pretty old and has been discussed on
51 * kbuild-devel a long time ago. I don't have a sensibly working
52 * internet connection right now, so I rather don't mention names
53 * without double checking.
54 *
55 * This code here has been based partially based on mkdep.c, which
56 * says the following about its history:
57 *
58 * Copyright abandoned, Michael Chastain, <mailto:[email protected]>.
59 * This is a C version of syncdep.pl by Werner Almesberger.
60 *
61 *
62 * It is invoked as
63 *
64 * fixdep <depfile> <target> <cmdline>
65 *
66 * and will read the dependency file <depfile>
67 *
68 * The transformed dependency snipped is written to stdout.
69 *
70 * It first generates a line
71 *
72 * cmd_<target> = <cmdline>
73 *
74 * and then basically copies the .<target>.d file to stdout, in the
75 * process filtering out the dependency on linux/autoconf.h and adding
76 * dependencies on include/config/my/option.h for every
77 * CONFIG_MY_OPTION encountered in any of the prequisites.
78 *
79 * It will also filter out all the dependencies on *.ver. We need
80 * to make sure that the generated version checksum are globally up
81 * to date before even starting the recursive build, so it's too late
82 * at this point anyway.
83 *
84 * The algorithm to grep for "CONFIG_..." is bit unusual, but should
85 * be fast ;-) We don't even try to really parse the header files, but
86 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
87 * be picked up as well. It's not a problem with respect to
88 * correctness, since that can only give too many dependencies, thus
89 * we cannot miss a rebuild. Since people tend to not mention totally
90 * unrelated CONFIG_ options all over the place, it's not an
91 * efficiency problem either.
92 *
93 * (Note: it'd be easy to port over the complete mkdep state machine,
94 * but I don't think the added complexity is worth it)
95 */
96/*
97 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
98 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
99 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
100 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
101 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
102 * those files will have correct dependencies.
103 */
104
105#include <sys/types.h>
106#include <sys/stat.h>
107#include <sys/mman.h>
108#include <unistd.h>
109#include <fcntl.h>
110#include <string.h>
111#include <stdlib.h>
112#include <stdio.h>
113#include <limits.h>
114#include <ctype.h>
115#include <arpa/inet.h>
116
117#define INT_CONF ntohl(0x434f4e46)
118#define INT_ONFI ntohl(0x4f4e4649)
119#define INT_NFIG ntohl(0x4e464947)
120#define INT_FIG_ ntohl(0x4649475f)
121
122char *target;
123char *depfile;
124char *cmdline;
125
126void usage(void)
127
128{
129 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
130 exit(1);
131}
132
133/*
134 * Print out the commandline prefixed with cmd_<target filename> :=
135 * If commandline contains '#' escape with '\' so make to not see
136 * the '#' as a start-of-comment symbol
137 **/
138void print_cmdline(void)
139{
140 char *p = cmdline;
141
142 printf("cmd_%s := ", target);
143 for (; *p; p++) {
144 if (*p == '#')
145 printf("\\");
146 printf("%c", *p);
147 }
148 printf("\n\n");
149}
150
151char * str_config = NULL;
152int size_config = 0;
153int len_config = 0;
154
155/*
156 * Grow the configuration string to a desired length.
157 * Usually the first growth is plenty.
158 */
159void grow_config(int len)
160{
161 while (len_config + len > size_config) {
162 if (size_config == 0)
163 size_config = 2048;
164 str_config = realloc(str_config, size_config *= 2);
165 if (str_config == NULL)
166 { perror("fixdep:malloc"); exit(1); }
167 }
168}
169
170
171
172/*
173 * Lookup a value in the configuration string.
174 */
175int is_defined_config(const char * name, int len)
176{
177 const char * pconfig;
178 const char * plast = str_config + len_config - len;
179 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
180 if (pconfig[ -1] == '\n'
181 && pconfig[len] == '\n'
182 && !memcmp(pconfig, name, len))
183 return 1;
184 }
185 return 0;
186}
187
188/*
189 * Add a new value to the configuration string.
190 */
191void define_config(const char * name, int len)
192{
193 grow_config(len + 1);
194
195 memcpy(str_config+len_config, name, len);
196 len_config += len;
197 str_config[len_config++] = '\n';
198}
199
200/*
201 * Clear the set of configuration strings.
202 */
203void clear_config(void)
204{
205 len_config = 0;
206 define_config("", 0);
207}
208
209/*
210 * Record the use of a CONFIG_* word.
211 */
212void use_config(char *m, int slen)
213{
214 char s[PATH_MAX];
215 char *p;
216
217 if (is_defined_config(m, slen))
218 return;
219
220 define_config(m, slen);
221
222 memcpy(s, m, slen); s[slen] = 0;
223
224 for (p = s; p < s + slen; p++) {
225 if (*p == '_')
226 *p = '/';
227 else
228 *p = tolower((int)*p);
229 }
230 printf(" $(wildcard include/config/%s.h) \\\n", s);
231}
232
233void parse_config_file(char *map, size_t len)
234{
235 int *end = (int *) (map + len);
236 /* start at +1, so that p can never be < map */
237 int *m = (int *) map + 1;
238 char *p, *q;
239
240 for (; m < end; m++) {
241 if (*m == INT_CONF) { p = (char *) m ; goto conf; }
242 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
243 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
244 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
245 continue;
246 conf:
247 if (p > map + len - 7)
248 continue;
249 if (memcmp(p, "CONFIG_", 7))
250 continue;
251 for (q = p + 7; q < map + len; q++) {
252 if (!(isalnum(*q) || *q == '_'))
253 goto found;
254 }
255 continue;
256
257 found:
258 use_config(p+7, q-p-7);
259 }
260}
261
262/* test is s ends in sub */
263int strrcmp(char *s, char *sub)
264{
265 int slen = strlen(s);
266 int sublen = strlen(sub);
267
268 if (sublen > slen)
269 return 1;
270
271 return memcmp(s + slen - sublen, sub, sublen);
272}
273
274void do_config_file(char *filename)
275{
276 struct stat st;
277 int fd;
278 void *map;
279
280 fd = open(filename, O_RDONLY);
281 if (fd < 0) {
282 fprintf(stderr, "fixdep: ");
283 perror(filename);
284 exit(2);
285 }
286 fstat(fd, &st);
287 if (st.st_size == 0) {
288 close(fd);
289 return;
290 }
291 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
292 if ((long) map == -1) {
293 perror("fixdep: mmap");
294 close(fd);
295 return;
296 }
297
298 parse_config_file(map, st.st_size);
299
300 munmap(map, st.st_size);
301
302 close(fd);
303}
304
305void parse_dep_file(void *map, size_t len)
306{
307 char *m = map;
308 char *end = m + len;
309 char *p;
310 char s[PATH_MAX];
311
312 p = strchr(m, ':');
313 if (!p) {
314 fprintf(stderr, "fixdep: parse error\n");
315 exit(1);
316 }
317 memcpy(s, m, p-m); s[p-m] = 0;
318 printf("deps_%s := \\\n", target);
319 m = p+1;
320
321 clear_config();
322
323 while (m < end) {
324 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
325 m++;
326 p = m;
327 while (p < end && *p != ' ') p++;
328 if (p == end) {
329 do p--; while (!isalnum(*p));
330 p++;
331 }
332 memcpy(s, m, p-m); s[p-m] = 0;
333 if (strrcmp(s, "include/linux/autoconf.h") &&
334 strrcmp(s, "arch/um/include/uml-config.h") &&
335 strrcmp(s, ".ver")) {
336 printf(" %s \\\n", s);
337 do_config_file(s);
338 }
339 m = p + 1;
340 }
341 printf("\n%s: $(deps_%s)\n\n", target, target);
342 printf("$(deps_%s):\n", target);
343}
344
345void print_deps(void)
346{
347 struct stat st;
348 int fd;
349 void *map;
350
351 fd = open(depfile, O_RDONLY);
352 if (fd < 0) {
353 fprintf(stderr, "fixdep: ");
354 perror(depfile);
355 exit(2);
356 }
357 fstat(fd, &st);
358 if (st.st_size == 0) {
359 fprintf(stderr,"fixdep: %s is empty\n",depfile);
360 close(fd);
361 return;
362 }
363 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
364 if ((long) map == -1) {
365 perror("fixdep: mmap");
366 close(fd);
367 return;
368 }
369
370 parse_dep_file(map, st.st_size);
371
372 munmap(map, st.st_size);
373
374 close(fd);
375}
376
377void traps(void)
378{
379 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
380
381 if (*(int *)test != INT_CONF) {
382 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
383 *(int *)test);
384 exit(2);
385 }
386}
387
388int main(int argc, char *argv[])
389{
390 traps();
391
392 if (argc != 4)
393 usage();
394
395 depfile = argv[1];
396 target = argv[2];
397 cmdline = argv[3];
398
399 print_cmdline();
400 print_deps();
401
402 return 0;
403}